The present invention relates to universal joints and to connection assemblies between a yoke and the shafts of a universal joint cross member.
Modern vehicles are often equipped with universal joints that comprise a cross member having four shafts or trunnions. Bearings are mounted on each shaft, and two yokes are mounted onto opposed pairs of shafts. The yokes are mounted at positions spaced 90.degree. relative to each other and are each connected to drive shafts. This arrangement allows rotation to be transmitted through varying angles between the drive shafts, through varying angles. This type of universal joint is particularly popular in heavy duty vehicles such as trucks.
Universal joint assemblies experience a great deal of stress and vibration and are exposed to a hostile environment on the underside of a vehicle. Thus, the connection between the yoke and the bearings should be secure and stable. Proper functioning of a universal joint also requires adequate lubrication between the bearings and the shafts. The universal joint designs utilized in the past have not always achieved these goals for yoke and cross member connections.
Conventionally, universal joints have utilized yokes that have full circular or cylindrical bores to receive a bearing and shaft. The full circular bore surrounds and supports the bearing during operation of the universal joint. Typically, the two shafts on the cross member are inserted within the bores in the yoke. The bearings are then inserted radially inwardly through the outer end of the bore and onto the shafts.
One problem with this arrangement is that since the bearings are inserted through the bores in the yoke after insertion of the shafts, the universal joint manufacturer has been unable to finally mount the bearings on the cross member shafts. Rather, the bearings must be mounted on the shaft at the vehicle assembly line. Typically, the assemblers at the vehicle assembly line are not as skilled in proper lubrication or assembly of universal joint bearings as assemblers at the universal joint manufacturer. For that reason, there has sometimes been improper lubrication or assembly of universal joints assembled on the assembly line.
To address this problem, universal joints have been developed wherein the cross member may be preassembled with its bearings already attached. In one prior art universal joint, the cross member shaft and bearing lay in a half-circle bore in the yoke. Metal straps surround the bearing and are connected to the yoke with bolts. This prior art assembly requires tight dimensional control.
In another prior art design, the bearing is connected to the yoke with bolts. The mounting bolts in this universal joint connection may become loose due to the high force moments. With either type of assembly, small locators on the bearing may be used to transmit rotation between the bearing and yoke. The small locators are placed relatively far from the centerline of the shaft. The locator provides a good deal of the reaction surface for torque transmission, and the distance from the shaft centerline results in relatively high force moments.